This story is not what it seems. This story is exactly what it seems. Sounds contradictory? It isn't. You just don't understand "dimentional physics"...
Seriously now, this thing is amazing, but also really not for everyone.
It starts as a trashy manga about men piloting giant semi-mechanical highschool girls, then turns into an interesting critique of the genre (girls with guns shooting things, all for male audience), then turns into an existential story about reality, psychosis, ego, post-truth, and the escapism of fiction.
(Apparently plumbing new depths of Goodreads obscurity here: this is Joshikouhei Vol.1 by Jiro Matsumoto. If there's ever an English edition I'll switch the review but I'm not exactly expecting one for reasons which may be clearer in a few paragraphs)
This isn't the first manga I've read about future war in which the warriors are genetically engineered teenage girls - it's not an unusual idea. And obviously it's not the only manga about mecha pilots being driven insane the more they interface with their machine. It is, though, the first I've read in which the mecha ARE the teenage girls.
There's no way to describe Joshikouhei without it sounding like trashy exploitation, and I doubt Matsumoto intended there to be. Takashi is a veteran in the "dimension wars" Earth is waging against its extra-dimensional colonies. For reasons, ah, yet to be explained the only effective weapon in these dimensional wars are 50 foot mecha which look like giant girls but have soldiers as pilots in their skull cockpits.
The pilots are both respected and pariahs. As well as the body-twisting nature of the dimensional war, the pilots' own brains are invariably corrupted as they start identifying themselves as the giant girls, and so a lot of Takashi's time is spent dealing with rogue "Assault Girl" units while dreading the day he starts getting texts and calls from imaginary besties - the first sign of the infectious madness.
There's... a lot going on here. Joshikouhei very much has its trashy cake and eats it - it's a satire of inane battle girl stories which has a vast amount of gore and nudity itself, though there's enough messed-up body horror thrown in to deflect any sense that this is simple titillation. It's also a gritty war comic which joyfully undercuts itself by having its battle-hardened warriors look so incongruous. The battle sequences are terrific - brutal, messy, but clearly choreographed. The black comedy works delightfully well. It's all just much, much better than you'd imagine it could be.
The thing it reminds me most of is 2000AD - the dark, ridiculous, spectacularly over the top Pat Mills-y side of 2000AD. Famously 2000AD "got sexy" for a while and decided to adult itself up and the results were dreadful. This is a glimpse of the kind of story we might have seen in a universe where that idea actually worked.